The intensity of solar radiation is highest at low latitudes (nearest to the equator), and the variation between summer and winter power output is also lower. At higher latitudes (such as in Britain and Germany) the seasonal variation is such that winter output is effectively negligible and other forms of supply are needed. British energy experts at the Department of Energy and Climate Change assessed that solar is effectively useless for the UK energy mix, but it was encouraged with Feed-In Tariffs for political reasons.

The intensity of solar radiation is highest at low latitudes (nearest to the equator), and the variation between summer and winter power output is also lower. At higher latitudes (such as in Britain and Germany) the seasonal variation is such that winter output is effectively negligible and other forms of supply are needed. British energy experts at the Department of Energy and Climate Change assessed that solar is effectively useless for the UK energy mix, but it was encouraged with Feed-In Tariffs for political reasons.

PV panels contain various toxic elements such as arsenic, cadmium and lead, and are not recycled. They are vulnerable to damage by storms, such as occurred when Hurricane Irma hit St. Thomas in 2017, and hurricane Maria hit Puerto Rico in 2018.

PV panels contain various toxic elements such as arsenic, cadmium and lead, and are not recycled. They are vulnerable to damage by storms, such as occurred when Hurricane Irma hit St. Thomas in 2017, and hurricane Maria hit Puerto Rico in 2018.

Solar installations require large areas of collectors, especially at higher latitudes where the intensity of sunlight is lower. This usually incurs an opportunity cost: land occupied by the solar installation might otherwise be used for agriculture, or be left (or allowed to revert to) a wild state, providing carbon sequestration and biodiversity services.

+

+

For example a proposed [https://www.clevehillsolar.com/ solar PV installation] on the North Kent coast in the South of England has drawn [https://whitstableviews.wordpress.com/2020/05/22/guest-blog-stop-graveney-marsh-solar-farm/ opposition] on the basis that the former farmland on which it would be built could alternatively be allowed to revert to salt marsh, with much greater benefits for biodiversity.

Latest revision as of 13:40, 23 May 2020

The sun's energy can be exploited in
passive solar buildings, used for
water heating or even
cooking, or used to generate electricity via
photovoltaic (PV) panels or
concentrating solar power (CSP) plants. Solar generator output varies with weather and obviously with day and night, with peak output around midday, declining to zero by evenings. This is usually a poor match for demand, resulting in a
"duck curve"
where demand rises quickly whilst solar output is declining, resulting in challenges to operators of electricity systems to ramp up output from other sources (usually gas) quickly enough to make up the shortfall.

Some Concentrating solar plants have been built using molten salt to not only transfer heat from the sun to turbines to generate electricity, but to store heat so that the plant can continue generating power past sunset. Whilst PV does generate some useful power under overcast conditions, CSP requires direct sunshine to operate, so is only suitable for areas with very little cloud cover. Both PV and CSP require large areas of panels or mirrors, which have to be kept clean, which can pose challenges in windy or dusty or snowy areas.

The intensity of solar radiation is highest at low latitudes (nearest to the equator), and the variation between summer and winter power output is also lower. At higher latitudes (such as in Britain and Germany) the seasonal variation is such that winter output is effectively negligible and other forms of supply are needed. British energy experts at the Department of Energy and Climate Change assessed that solar is effectively useless for the UK energy mix, but it was encouraged with Feed-In Tariffs for political reasons.

Solar panels destroyed by Hurricane Irma: St Thomas, 2017

PV panels contain various toxic elements such as arsenic, cadmium and lead, and are not recycled. They are vulnerable to damage by storms, such as occurred when Hurricane Irma hit St. Thomas in 2017, and hurricane Maria hit Puerto Rico in 2018.

The Capacity Factor of solar PV installations vary from almost 30% in Arizona to under 10% in the UK.

Taking the United Kingdom as a case study, this paper describes current energy use and a range of sustainable energy options for the future, including solar power and other renewables. I focus on the the area involved in collecting, converting, and delivering sustainable energy, looking in particular detail at the potential role of solar power.

rectennas

A new kind of nanoscale rectenna (half antenna and half rectifier) can convert solar and infrared into electricity, plus be tuned to nearly any other frequency as a detector.

Right now efficiency is only one percent, but professor Baratunde Cola and colleagues at the Georgia Institute of Technology (Georgia Tech, Atlanta) convincingly argue that they can achieve 40 percent broad spectrum efficiency (double that of silicon and more even than multi-junction gallium arsenide) at a one-tenth of the cost of conventional solar cells (and with an upper limit of 90 percent efficiency for single wavelength conversion).

Chemical

solar energy splitting CO2 and H2O to CO and H2 syngas

a team of scientists announced in the journal Science that they have created a device that absorbs carbon dioxide from the atmosphere and uses sunlight to break it into a mix of carbon monoxide and hydrogen called synthesis gas or “syngas,” that can be used directly or turned into diesel or other liquid fuels,

the device’s chemical catalyst—necessary for breaking down the CO2—is not a costly metal such as platinum, palladium, or silver but a “nanoflake tungsten diselenide.”

Most artificial photosynthesis approaches focus on making hydrogen. Modifying CO2, as plants and microbes do, is more chemically complex. Asadi et al. report that fashioning WSe2 and related electrochemical catalysts into nanometer-scale flakes greatly improves their activity for the reduction of CO2 to CO. An ionic liquid reaction medium further enhances efficiency. An artificial leaf with WSe2 reduced CO2 on one side while a cobalt catalyst oxidized water on the other side.

Conversion of carbon dioxide (CO2) into fuels is an attractive solution to many energy and environmental challenges. However, the chemical inertness of CO2 renders many electrochemical and photochemical conversion processes inefficient. We report a transition metal dichalcogenide nanoarchitecture for catalytic electrochemical CO2 conversion to carbon monoxide (CO) in an ionic liquid. We found that tungsten diselenide nanoflakes show a current density of 18.95 milliamperes per square centimeter, CO faradaic efficiency of 24%, and CO formation turnover frequency of 0.28 per second at a low overpotential of 54 millivolts. We also applied this catalyst in a light-harvesting artificial leaf platform that concurrently oxidized water in the absence of any external potential.

Scientists have reverse engineered a biosynthetic pathway for more effective carbon fixation that is based on a new CO2-fixing enzyme that is nearly 20 times faster than the most prevalent enzyme in nature responsible for capturing CO2 in plants by using sunlight as energy.

Despite the vast diversity of organisms on the planet that express enzymes for the conversion of carbon dioxide into such organic compounds as sugars -- as plants do through photosynthesis -- the efforts to harness these capabilities to transform CO2 into high-value products such as biofuel and renewable chemicals have met with limited success. While increasing concentration of CO2 in the atmosphere poses a challenge, researchers also see it as an opportunity.

Now a team from the Max-Planck-Institute (MPI) for Terrestrial Microbiology in Marburg, Germany, by tapping the DNA synthesis expertise of the U.S. Department of Energy Joint Genome Institute (DOE JGI), has reverse engineered a biosynthetic pathway for more effective carbon fixation. This novel pathway is based on a new CO2-fixing enzyme that is nearly 20 times faster than the most prevalent enzyme in nature responsible for capturing CO2 in plants by using sunlight as energy. The study was published in the November 18, 2016 issue of Science.

Ricardo Grau-Crespo / University of Reading

University of Reading scientists have designed materials which could be used to combat global warming.

The hypothetical materials have the precise molecular structure needed to absorb harmful carbon dioxide emissions and convert them into useful chemicals such as methanol by using sunlight.

The pioneering research, conducted by a team in Reading's Chemistry Department, could pave the way for other researchers to create porous photocatalyst materials.

Theoretically, the materials could also be used to absorb solar energy and split water into oxygen and hydrogen elements. These could then be recombined in fuel cells to produce energy and water.

Dr Ricardo Grau-Crespo, who led the research, said: “This might look like science fiction, but the possibility of synthesizing these versatile materials is very real, and could be achieved within a year based on our designs.

Scientists have theoretically designed a new material that could help supply the world with clean energy by turning water into fuel, using just the power of the sun.

Chemists at the University of Reading say a new catalyst, which mimics the way plants absorb energy from the sun, could make the energy-sapping job of splitting water into hydrogen and oxygen relatively easy.

As well as potentially being able to produce hydrogen for fuel cells, the complex new material could also be used to turn carbon dioxide from the air into a carbon-based fuel, such as methanol.

Dr Ricardo Grau-Crespo, from the Chemistry Department of the University of Reading, led the team that made the discovery.

"Finding a material that can help create readily available fuels is one of the holy grails of science," he said.

"While we still have a long way to go, our new findings could be a significant step forward in the search for cheaper, environmentally-friendly fuels to power the future."

Splitting water into hydrogen and oxygen is an energy-intensive process, which currently requires much more energy in from electricity than comes out in usable fuel.

To make the process more efficient, scientists use a photocatalyst - a material that absorbs light from the sun and uses it to excite electrons to higher energy levels. These excited electrons, and the empty spaces they leave behind, are then capable of driving forward the two half-reactions required to split water into oxygen and hydrogen.

Unfortunately, finding a good photocatalyst is tricky as its properties have to be very precise to allow the reaction to take place. One of the best photocatalyst material available, titanium oxide, is too inefficient to produce more than a tiny amount of hydrogen, as it can only absorb energy from ultraviolet light.

The Reading-led team used supercomputer simulations to look at many different candidates as potential photocatalysts for fuel production reactions.

In new research, published in the Royal Society of Chemistry's Journal of Materials Chemistry A, they found that some metal-organic frameworks, which combine metal atoms and organic molecules, exhibit the ideal electronic structure required to catalyse these reactions.

Dr Grau-Crespo said: "Our research is inspired by nature, as porphyrin is related to chlorophylls, the green pigments which allow plants to convert sunlight into chemical energy.

"The challenge now is to incorporate these wonderful natural catalysts into materials capable of doing the specific chemical job we need. If we can do this, it could lead to highly-efficient conversion of solar energy to chemical energy - providing a clean, storable and transferrable source of energy."

This new research was a collaboration between the University of Reading, UK, and the University Pablo de Olavide in Seville, Spain, and was funded by an International Exchange grant from the Royal Society.

The development of cheap, efficient techniques to carry out the photocatalytic splitting of water would permit the generation of a clean fuel (hydrogen) at low negative environmental impact.

Of similar interest is the photocatalytic reduction of CO2, which would allow the synthetic production of carbon-containing fuels (e.g. methanol) and simultaneously contribute to recycle CO2 from the environment. It is clear that the development of efficient technologies to carry out these energetically up-hill reactions using solar energy would be greatly beneficial, and therefore, many research efforts are being devoted to it, in particular to the search for adequate photocatalysts. This research was initially focused on traditional inorganic semiconductors, such as TiO2 and CdS, but it has now extended to a wider class of materials, including nanostructures such as fullerenes, nanotubes and graphene-like 2D solids. On the other hand, water splitting and CO2 reduction are at the core of natural photosynthetic reactions, so the study of the related natural processes can help finding artificial routes for these reactions. Bioinspired molecular photocatalysts have been largely studied in recent years.

Besides Mn-complexes that are close to natural photosynthesis reactions, porphyrins have also been identified as active molecular centres for artificial photosynthesis. One drawback of molecular systems from a practical point of view is their recyclability, as the separation of the catalysts from liquid media is very difficult. To overcome this problem, one attractive route is their immobilization in solid hosts. Metal–organic frameworks (MOFs) have appeared as promising hosts, where catalytic centres can be encapsulated or moreover be part of the constituents of the materials. After pioneering work by Suslick and co-workers, a number of porphyrin-based MOFs have been reported, including some with photocatalytic properties.

Achieving solar-to-hydrogen efficiencies above 15% is key for the commercial success of photoelectrochemical water-splitting devices. While tandem cells can reach those efficiencies, increasing the catalytic activity and long-term stability remains a signiﬁcant challenge. Here we show that annealing a bilayer of amorphous titanium dioxide (TiOx) and molybdenum sulﬁde(MoSx) deposited onto GaInP2 results in a photocathode with high catalytic activity (current density of 11 mA cm−2 at 0 V versus the reversible hydrogen electrode under 1 sun illumination) and stability (retention of 80% of initial photocurrent density over a 20 h durability test) for the hydrogen evolution reaction. Microscopy and spectroscopy reveal that annealing results in a graded MoSx/MoOx/TiO2 layer that retains much of the high catalytic activity of amorphous MoSx but with stability similar to crystalline MoS2. Our ﬁndings demonstrate the potential of utilizing a hybridized, heterogeneous surface layer as a cost-effective catalytic and protective interface for solar hydrogen production.

Scientists at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have developed a “better way” to make hydrogen using renewable energy according to a paper published this month in Nature Energy.

One such method includes the use of photoelectrochemical (PEC) devices that can absorb sunlight and use it directly to split water molecules. Broadly speaking, these devices can convert the energy in sunlight into hydrogen and oxygen without the need for natural gas and at potentially higher efficiencies than electrolysis. These PEC devices have significant promise but scientists have struggled to produce a design that is durable enough to become commercially viable. However, according to the new paper, researchers have made a significant stride in improving the durability of PEC devices, bringing them one step closer to commercialization.

When and if it gets built the Valhalla project will consist of a 600 MW solar farm and a 300 MW pumped hydro plant which, it is claimed, will in combination deliver continuous baseload power to Northern Chile. If the project works as planned it will indeed deliver continuous baseload power, but only enough to fill about 5% of Northern Chile’s baseload demand. However, it would be the first to demonstrate that baseload power can be generated from a utility-scale PV plant. Development is presently on hold while Valhalla seeks $1.2 billion in financing.

The Valhalla project will send intermittent generation from the 600 MW Cielos de Tarapacá solar PV farm to the 300 MW Espejo de Tarapacá pumped hydro plant in order to convert it into baseload power.

Millions of floating islands, clustered together, that convert carbon dioxide to methanol fuel could help reduce the amount of green house gases in the atmosphere, according to researchers from Norway and Switzerland.

floating

On a vast manmade lake on the outskirts of London, work is nearing completion on what will soon be Europe’s largest floating solar power farm – and will briefly be the world’s biggest. But few are likely to see the 23,000 solar panels on the Queen Elizabeth II reservoir at Walton-on-Thames, which is invisible to all but Heathrow passengers and a few flats in neighbouring estates. “This will be the biggest floating solar farm in the world for a time - others are under construction,” said Angus Berry, energy manager for Thames Water, which owns the site. “We are leading the way, but we hope that others will follow, in the UK and abroad.”

In the not so distant future, the power we need could very well be provided by floating solar power plants that are offshore. Wind farms have become very popular in recent years and now experts are looking at ways to create sustainable energy without having to develop land. The solution: use the sea to house these structures. The Vienna University of Technology is currently working on such a technology. They are calling it the Heliofloat. It consists of a seafaring solar power station that has an open bottom and is flexible, about the size of a football field. Interestingly, they are designing them so that multiple platforms can conjoin to create a solar power grid, if need be. Rugged in their design, the floats will not capsize even in severe weather. Constructed using barrels to stay afloat with an open bottom that traps air, the floatables also prevent capsizing during even the worst of storms. There’s no word yet on when these new contraptions will be able to power our homes and businesses, but it’s a pretty innovative and cool idea nonetheless.

Millions of floating islands, clustered together, that convert carbon dioxide to methanol fuel could help reduce the amount of green house gases in the atmosphere, according to researchers from Norway and Switzerland.

Airborne

StratoSolar PV power plants are constructed from buoyant, rigid, platforms that support large arrays of photovoltaic (PV) panels on their top surface. They float stationary in the low stratosphere at 20 kilometer (km) altitude (65,616 feet) for the thirty year life of the power plants. They are connected to the ground and held in place with strong and light Kevlar or UHMPE tethers. The tethers also support High Voltage (HV) power lines that transfer the electric power generated by the PV panels to the ground. Excess buoyancy in the floating platforms pre-tension the tethers and allow the platform to resist wind forces with small horizontal deflections. The pictures below show the size of a range of power plants from 5 Mega Watts rated power (MWp) to 10.3 Giga Watts rated power (GWp ).

Environmental - waste - disposal/recycling

Solar panels glimmering in the sun are an icon of all that is green. But while generating electricity through photovoltaics is indeed better for the environment than burning fossil fuels, several incidents have linked the manufacture of these shining symbols of environmental virtue to a trail of chemical pollution. And it turns out that the time it takes to compensate for the energy used and the greenhouse gases emitted in photovoltaic panel production varies substantially by technology and geography.

That’s the bad news. The good news is that the industry could readily eliminate many of the damaging side effects that do exist. Indeed, pressure for it to do so is mounting, in part because, since 2008, photovoltaics manufacturing has moved from Europe, Japan, and the United States to China, Malaysia, the Philippines, and Taiwan; today nearly half the world’s photovoltaics are manufactured in China. As a result, although the overall track record for the industry is good, the countries that produce the most photovoltaics today typically do the worst job of protecting the environment and their workers.

The issue of how to dispose of hazardous waste from ageing panels casts a shadow over the drive towards renewable energy and away from fossil fuels

China will have the world’s worst problem with ageing solar panels in less than two decades, according to a recent industry estimate.

Lu Fang, secretary general of the photovoltaics decision in the China Renewable Energy Society, wrote in an article circulating on mainland social media this month that the country’s cumulative capacity of retired panels would reach up to 70 gigawatts (GW) by 2034. That is three times the scale of the Three Gorges Dam, the world’s largest hydropower project, by power production. By 2050 these waste panels would add up to 20 million tonnes, or 2,000 times the weight of the Eiffel Tower, according to Lu.

solar plants are relatively short-lived, and the government does not have any retirement plan for them yet. A panel’s lifespan ranges from 20 to 30 years, depending on the environment in which they are used, according to the US Department of Energy. High temperatures can accelerate the ageing process for solar cells, while other negative factors – such as the weight of snow or dust storms – could cause material fatigue on the surface and internal electric circuits, gradually reducing the panel’s power output.

A solar panel contains metals such as lead and copper and also has an aluminium frame. The solar cells are made up of pure, crystallised silicon wrapped under a thick layer of plastic membrane for protection. In Europe, some companies are reported to have developed sophisticated technology to reclaim more than 90 per cent of the materials.

China’s solar power plants are mostly located in poor, remote regions such as the Gobi in Inner Mongolia, while the majority of recycling industries are in developed areas along the Pacific coast. Transporting these bulky panels over long distances could be very costly, Tian said. Another cost comes from separating and purifying the waste materials, an industrial process that not only requires plenty of labour and electricity input, but also chemicals such as acids that could cause harm to the environment. “If a recycling plant carries out every step by the book to achieve low pollutant emission, their products can end up being more expensive than new raw materials,”

Solar photovoltaic systems, solar thermal and concentrating solar power technologies have a life expectancy of upwards of 30 years. As the volume of solar installations in the US grows, the industry is planning ahead to create a national PV module recycling program.

The last few years have seen growing concern over what happens to solar panels at the end of their life. Consider the following statements:

The problem of solar panel disposal “will explode with full force in two or three decades and wreck the environment” because it “is a huge amount of waste and they are not easy to recycle.”

“The reality is that there is a problem now, and it’s only going to get larger, expanding as rapidly as the PV industry expanded 10 years ago.”

“Contrary to previous assumptions, pollutants such as lead or carcinogenic cadmium can be almost completely washed out of the fragments of solar modules over a period of several months, for example by rainwater.”

Were these statements made by the right-wing Heritage Foundation? Koch-funded global warming deniers? The editorial board of the Wall Street Journal?

Concentrating

Ivanpah, Solana and Crescent Dunes, regarded as landmark in the history of CSP plants development, have attracted attention of people across the world, especially in China market. Given that Crescent Dunes has been in operation for more than six month since formally put into operation in Feburary this year, CSPPLAZA makes tables of three plants’ electricity production to see whether they perform well.

Concentrated solar power may surpass photovoltaics as the solar technology of choice because the sun's heat is more easily stored

In the United States, concentrated solar power (CSP) manifested in the 1980s as nine power plants in Southern California using trough-shaped mirrors to concentrate energy on a circulating heat transfer fluid. The fluid, often a synthetic oil, then heats up a molten salt to as high as 350 degrees Celsius, which then boils water to drive a turbine.

Crescent Dunes

A California firm is converting sunlight to heat and storing it in molten salt so it can supply electricity when the wind is calm or the sun isn’t shining

Deep in the Nevada desert, halfway between Las Vegas and Reno, a lone white tower stands 195 meters tall, gleaming like a beacon. It is surrounded by more than 10,000 billboard-size mirrors focusing the sun’s rays on its tip

The facility is touted as being the first solar power plant that can store more than 10 hours of electricity, which translates into 1,100 megawatt-hours, enough to power 75,000 homes

Although a few other plants like the Solana Generating Station in Arizona have used molten salt as a storage medium, they heat the salt indirectly, using solar energy to first heat other fluids such as oil.

when the cost of even the best battery technology is taken into consideration, photovoltaics are more expensive than concentrating solar power, which is now down to 10 to 12 cents per kilowatt-hour.

Crescent Dunes is already nearly six times bigger than Torresol Energy’s 20 megawatt demonstration­ scale plant that was completed in 2011 in Spain. And SolarReserve is planning to break ground on a second plant roughly the same size as Crescent Dunes in South Africa later this year.

Found in the middle of the dust and rocks of the Nevada desert, not to mention the blazing Sun above, Crescent Dunes‘ solar oasis can be found.

Composed of a tall central tower surrounded by a total of 10,437 glass panels, with more than one million square meters (~10.8 million square feet) of glass, this solar oasis is capable of storing energy, enough to supply electricity to 75000 households during peak demand periods, 24/7.

The central tower then secretes a reservoir of potassium and sodium nitrate—about 25,000 metric tonnes (~28,000 US tons) of it—heated in advance to 288°C (550°F), at which temperature the mixture is a clear, water-like liquid.

This is then circulated in narrow, thin-walled tubes, rising dramatically in temperature when exposed to the fearsome, concentrated sunlight at the top of the tower. “We heat it to 560°C (1040°F),” says Smith, “it flows back down the tower and we capture it in a large tank.”

The California Public Utilities Commission (CPUC) has approved PG&E’s December 18 request for a Forbearance Agreement for Ivanpah Units 1 and 3, giving the two units at least six months, and possibly a year, to meet current production targets of 448,000 MWh annually.

Sandstone

SolarReserve CEO Kevin Smith told the Las Vegas Review-Journal that the $5 billion endeavor would generate between 1,500 and 2,000 megawatts of power, enough to power about 1 million homes. That amount of power is as much as a nuclear power plant, or the 2,000-megawatt Hoover Dam and far bigger than any other existing solar facility on Earth, the Review-Journal pointed out.

A California-based energy company announced plans Tuesday to build the world’s largest solar project in Nevada, a $5 billion endeavor involving at least 100,000 mirrors and 10 towers as tall as any building in the state.

SolarReserve’s Sandstone project would include up to 10 concentrated solar arrays, each equipped with a molten salt system capable of storing the sun’s energy to generate power after dark, CEO Kevin Smith said.

The company already has built one such array, the 110-megawatt Crescent Dunes Solar Energy Plant, on 1,600 acres of federal land outside of Tonopah, 225 miles northwest of Las Vegas. The $1 billion array began delivering power to NV Energy late last year.

Smith said project Sandstone would generate between 1,500 and 2,000 megawatts, enough to supply about a million homes. That’s on par with a nuclear power plant or the Hoover Dam and far bigger than any of the world’s existing solar facilities.

Spain

Euan Mearn’s recent Red Eléctrica de España (REE) post drew my attention to the fact that REE has now begun to show grid data for solar PV and concentrated solar power (CSP) generation separately instead of lumping them together. In this post I use the REE data to review the performance of Spain’s CSP plants and to check among other things whether the claim that they are capable of providing baseload generation, as this 2011 Forbes article claimed, holds up in the light of operating experience. Spain is a good case study because the lion’s share of world CSP capacity (2.3 of 3.4GW in 2013) is installed there.

Gemasolar

Heat of up to 900C is used to warm molten salt tanks, which create steam to power the £260million station's turbines. But, unlike all other solar power stations, the heat stored in these tanks can be released for up to 15 hours overnight, or during periods without sunlight. The regular sunshine in southern Spain means the facility can therefore operate through most nights, guaranteeing electrical production for a minimum of 270 days per year, up to three times more than other renewable energies. The project, a joint venture between Abu Dhabu energy company Masdar and Spanish engineering firm SENER called Torresol Energy, took two years to construct at a cost of £260million. It is expected to produce 110 GWh/year - enough to power 25,000 homes in the Andalucia region.

North Africa

TuNur, a small company based in the UK, has applied to the Tunisian Government to begin construction of a 4.5GW concentrated solar power (CSP) project in the Sahara Desert.

The first stage of Sahara solar will see a 250MW CSP tower constructed, along with a dedicated transmission line through the Mediterranean Sea to Malta. This phase is estimated to cost €85m, and a further €1.6bn for the cable link.

As such, the cost of power is expected to be 8.73 cents per kilowatt hour (c/kWh). Solar PV is estimated to cost 7.7c/kWh for generation alone in Tunisia. Elsewhere within the Middle East and Northern Africa (MENA) region, the price of CSP has already seen dramatic reductions.

Earlier this year, the Dubai Electricity and Water Authority announced that the fourth phase of its 200MW Mohammed bin Rashid Al Maktoum solar park included bids as low as 6.3c/kWh, while SolarReserve in South Australia achieved prices as low as 5.2c/KWh, and its project in Chile in 2016 hit 5.7c/kWh.

As the cost of CSP has dropped it has become increasingly competitive with other sources of dispatchable power. “We believe that by deploying CSP in Tunisia and generating the power there, that even with the additional costs of the transmission links to Europe we are a much more competitive solution for the Europe markets than those alternatives,” says Rich.

Furthermore, CSP offers a host of local benefits. TuNurs alone promises up to 20,000 new jobs. “With CSP technology, up to 60% of capex can, in theory, come from local companies, so there’s a huge foreign direct investment and socio-economic development opportunity for Tunisia without restricting Tunisia from also doing this for their domestic supply,” says Rich.

CSP arguably provides greater local investment opportunities than a PV project would, as there is a higher percentage of local manufacturing; PV panels are generally imported, so require less on-site construction, creating fewer local jobs. “CSP is more of an infrastructure project whereas PV has become quite a simplified commodity almost,” Rich says, adding that “There are more challenges, but the construction industry is gearing up and has already geared up to be able to accommodate that.”

bird etc casualties

America’s second solar power tower, the 110 MW Crescent Dunes project, the first US power tower to include storage, has been undergoing final commissioning (testing) at Tonopah in Nevada, where it will supply power for Las Vegas till midnight.

So SolarReserve is putting the thousands of heliostats (mirrors) through their paces to make sure everything works.

One of the tests is of standby position. (Standby is when the heliostats are waiting to go to work making electricity by focusing on the tower receiver. During standby they are not aimed at the tower receiver, but somewhere in the air.)

Originally, the standby position was to create a tight circle of solar flux you can actually see above the tower.

But when the engineers focused 3,000 heliostats there on January 14th, 115 birds were killed as they flew through the concentrated solar flux at the focal point where all the reflections met.

“So what we did is we spread them over a several hundred meters of a sort of ‘pancake’ shape so any one point is safe for birds — it’s 4 suns or less.”

“We have had zero bird fatalities since we implemented this solution in January, despite being in the standby position as well as flux on the receiver for most days since then,” he said. “This change appears to have fully corrected the problem.”

molten silicon storage

According to the team from the Solar Energy Institute of the Universidad Politécnica de Madrid (UPM), up to 1MWh of energy can be stored in just one cubic metre of molten silicon. Combined with the fact that silicon is the most abundant element in the Earth’s crust, the technology holds a promise for solving the problem of intermittency of renewable power generation. The system, described in an article in the Energy journal, stores energy from solar rays at very high temperatures of up to 1400°C. The energy can be recovered when needed through a thermal generator. “At such high temperatures, silicon intensely shines in the same way that the sun does; thus photovoltaic cells, thermophotovoltaic cells in this case, can be used to convert this incandescent radiation into electricity,” explained Alejandro Datas, who led the research. “The use of thermophotovoltaic cells is key in this system, since any other type of generator would hardly work at extreme temperatures.” With conversion efficiency of up to 50 per cent, these thermophotovoltaic cells can produce 100 times more electric power per unit area than conventional solar cells. The technology is quite similar to the existing concepts of storing solar power in molten salts. However, the salts are not only ten times less efficient, they are also more expensive and harder to obtain. The team is currently awaiting a US patent and has started building a laboratory scale prototype that would pave the way for a commercial product. In addition to thermal solar power plants, the researchers envisage that the system could be used in the housing sector to provide electricity and heating to residential and office buildings.

A 5-minute 40-second overview of the Energy Towers technology. Developed at the Technion-Israel Institute of Technology by Prof. Dan Zaslavsky, this is the most cost-effective technology for supplying zero-emission electricity from renewable sources. Electricity can be produced more cheaply than with virtually any other technology, including wind turbine, solar, coal, natural gas and nuclear. There also are 13 beneficial byproducts, including the ability to cheaply desalinate sea water in huge volumes.

Why? Solar towers capture solar energy to heat air under an expansive collector zone. Based on the principle that heat rises, this air flows towards the center of the collector through electricity-generating turbines and up and out of the tower, like a chimney. When built, the tower will be about 750 meters high and could produce enough electricity to power approximately 500 households.

The sun's radiation is used to heat a large body of air under an expansive collector zone, which is then forced by the laws of physics (hot air rises) to move as a hot wind through large turbines to generate electricity.

A single power station development will have the capacity to supply renewable energy to more than 100,000 typical American households or remove the equivalent of 220,000 typical motor vehicles from the roads.

Land use

Solar installations require large areas of collectors, especially at higher latitudes where the intensity of sunlight is lower. This usually incurs an opportunity cost: land occupied by the solar installation might otherwise be used for agriculture, or be left (or allowed to revert to) a wild state, providing carbon sequestration and biodiversity services.

For example a proposed solar PV installation on the North Kent coast in the South of England has drawn opposition on the basis that the former farmland on which it would be built could alternatively be allowed to revert to salt marsh, with much greater benefits for biodiversity.